$.validator.addMethod(
    "dateVN",
    function(value, element) {
        return this.optional(element) || /^(0?[1-9]|[12]\d|3[01])[\.\/\-](0?[1-9]|1[012])[\.\/\-]([12]\d)?(\d\d)$/.test(value);
    },
    "Please enter a date in the format dd/mm/yyyy."
);

/*$.validator.addMethod(
    "notFutureDate",
    function(value, element) {
        var today = new Date();
        var selected = $.datepicker.parseDate('dd/mm/yy', value);
        return this.optional(element) || selected.getTime() <= today.getTime();
    },
    "You cannot select a future date."
);*/